Process for producing glues and adhesives from keratin protein materials



quality;

PatentedApr. 30, 1946 I PROCESS FOR PRODUCING GLUES AND AD- HESIVES FROM KERATIN PROTEIN MA- TERIALS George H. Brother and Charles H. Binkley, Berkeley, Calif., assignors to Claude R. Wickard, as Secretary of Agriculture of the United States of America, and his successors in office No Drawing. Application June 30, 1942, Serial No. 449,180

(Granted under the act ofMarch 3, 1883, as

2 Claims.

amended April 30, 1928; 370 O. G. 75'l)' This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described and claimed, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to the use of keratin protein materials, and has among its objects the production of glues or adhesives from such materials; the utilization of waste keratin material, such as feathers, hair or hoofs, in the preparation of adhesives; the production of adhesives and glues from mixtures of waste keratin materials with known adhesives, such as blood, casein, bone glue or hide glue, thereby reducing the cost of the adhesive without reducing the and the utilization of waste or low grade keratin materials, alone or in mixture with other glue materials, in the preparation of adhesives suitable for use with plywood, corrugated paper, cardboard, and the like.

Keratin materials, such as horn, hoof, hair, feathers, etc., are known to be the most permanent and stable form of protein material.

structurally they differ from alb-umins, such as egg and blood, and from globulins, such as casein, soybean protein, peanut protein, etc., by consisting of extended fiber-like molecular chains, oriented normal to the fiber axis, as shown by X-ray diffraction patterns. Chemically these materials are so stable and resistant to change that it has not been possible heretofore to disperse them in useful forms without so breaking them down as to render the resultant product of little practical value as glues or adhesives.

Previous attempts to prepare adhesives from keratins have used such processes as treating materials, such as hor hoof, hair, and so forth, with steam at high pressures (3 to 4 atmospheres) for several hours; heating the dry material at high pressures and temperatures for extended periods; heating under high pressure with aqueous alkaline solutions; treating with caustic solution at or near 212 F.; and treating with strong caustic solution.

All these methods employed for the dispersion of keratin protein material for adhesives are extremely violent and excessive break-down in the structure of the protein molecule results. That this is the case is indicated by the well known fact that evolution of hydrogen sulphide accompanies heating keratin with steam under pres sure for extended periods. Under these conditions, the production of glues having good strength is not possible.

Our invention produces a product different from any produced before in that the keratin protein is not excessively broken down by our treatment, so adhesives produced from it are strong and resistant. It is therefore possible to utilize keratin protein materials such as chicken feathers, hog bristles, hoof and horn meal and the like, which are for the most part waste material and for which no satisfactory use has been developed.

In order to produce adhesives which fulfill the objectives of this invention and which may be applied in the art to advantage, the following general procedure must be followed: Dry keratin material, such as chicken feathers, hog bristles, hair, hoof or horn shavings, is mixed with sodium sulphide and caustic soda solutions of not over 2.5% concentration and heated in an autoclave at a moderate pressure for a few minutes. The product may be filtered to produce a liquid glue, but it is usually dried in thin films (30 g. per sq. ft.) by circulating air at not above 104 F. If dried in much thicker films or at higher temperatures, the dry glue powder will not readily redisperse in water. When dried to 812% moisture content the glue flakes are reduced to powder in ball mills, screenedthrough mesh screens to remove any undispersed keratin and the powder is ready for adhesive application. This powder, if kept dry (ii-12% moisture content) will not deteriorate, so may be stored until needed. To prepare the adhesive, it is used alone or mixed with dried blood, casein glue, animal glue or other glue material and stirred into water to give a glue of the desired viscosity.

If mixed with blood, the mixing may take place before the keratin is dried in films. The dried blood need not be the refined product, but the cheapest grade of fertilizer blood. Mixing with casein glue can best be effected in the powdered state, but mixing with bone or hide glue requires special precautions, as will be shown. Mixtures of keratin glue with blood or casein glues will be found after setting-up to have as good strength and water resistance as the unmixed commercial material. Mixtures of keratin glue with bone or hide glues may be made to show about as rapid set on paper or cardboard and the water resist ance is much superior to that of bone or hide glue.

In order to more clearly illustrate our invention, the following examples are given. It has been found that somewhat different treatments are necessary to produce dispersions from poul- 2 s earer try body feathers. quills. holbrhties and cattle orhorsehoofmaterial. Ailarewithinthelimits ofthegeneralprccedureasoutiinedahovemt therearediflerencesindetaiLwhichwiilbeshown inspeciiicexamples. Itistobeunderstoodtmt these examplesareforthepurposeofilhastrsting theinventionandarenotinanysensetobe takenasrestricting itsscope.

Example 1.200 grams of chicken body feafliers is worked into 1000 ml. of a solution-that is 1% causticsodaand 0.5% sodiumsuiflde (60%fused, these-called double strength). Awettingagent,

" such as Tergitol Penetrant '7" (a higher sodium alkyl sulphate, specifically, 3.9 diethyltridecsme- 6 sodium sulphate), may be used to facilitate wetting the feathers with the solution. The mixtureisheatedto80C.andmaintainedat80 to90C.onasteambathfor20minutes.while beingcontinuouslystirred. Theresultingdigest is-driedasathiniilm (30gramspe'rsquare foot) on a glass plate at room temperature (25' 0.). Thedriedfllmisreducedtoapowderina balimiilandthisisscreenedthroughaiwmesh screentoseparatethegluepowdcrfromtheundigested portions. Aworkingglueispreparedby mixingwgram'softhis'powdered gluewith 100 ml. water, allowing to stand about an hour, then again thoroughly stirring before appl in The viseosityiswithintherangeofthatofaverage joint and plywood glues. ThepH is about 10.5. Plywoodispreparedbyapplyingthegiuetowood veneersandpressingtheseatmpoundsper squareinchforminutesat105' (2.,thencooiing under pressure. When allowed to set over night, the glue line shows strength comparable withthatofeomniercialplywood. Itisnotwater resistant enough to comply with the Bureau of StandardstestCS45-40(19i0),formoistureresistant plywood.

Example 2.--200gramsof chicken quiiifeatheis isworkedinto1000mi.ofa1% sodiumsuiiide (60% fused) solution, with or without the presenceofawettingagent,andthemixtureisheated for 30 minutes in an autoclave at 18 poundssteam pressure. 50mi.ofa20% eaustiesoiuflonisthen addedandthemixtureismaintainedat80to90' C. for minutes and constanth' stirred. The digestisdriedinaiilm,asinExample1,and theworkingglueispreparedfromthepowder similarly. It has a somewhat lower viscosity than the glue of (1) and in consequence better spread. The pHisahout10.5. Itmaybeused with fair results as a cold glue. It produces a stronger plywood with wood veneers. united in a hot press as in (1). The glue line is not water resistantwhenflrstmade,butafteraboutsix weeks it becomes resistant enough to pass the Bureau of Standards test 08% 45-40 (1940) Example 31-200 gramsofmixedbodyandquiii chicken feathers is worked into 1000 ml. of a 1% sodium sulfide (60% fused) solution. with or without the presence of a wetting agent, and the mixture isheated for 30 minutes in anautoclave at 18 pounds pressure. 50ml. of'a caustic I 55 withstirringwith100mhofa1% aqueouscaiissolution' is then added and the mixture thor- -It isfurtherheated'for5minutes in the autoclave at 7 pressure. The dried in'fiims, powdered andscreened. as'in Example 1. The working glue is prepared bystirringm'gramsofthepowderedgiueintolm m1. of water. The pH is about 10.5, and the viscosity and spreading properties are comparable to those oi! averageeasein glues. Wood veneers united asinExampiel are found tohave about the strength as'those united with average casein 75 45-40 (1940) test.

55isabout12.2. Thismaterialisnotsuitableior giueawhensetovernightbuton'agein'mtbe mthiuermasdoesthewaterresistauee. untiiaiterdweemtheplieswillpassthenmeau of8tandardstestC845-40 (1010) forcommer- 5 ciaiplswood.

lumpielr-imgramsofslaughterhousehog bristleadrybutnotcleanedisautoclavedmim ml. ofa 1.5% sodium sulfide (80% fused) solution at 18 pounds pressure for 30 minutes. '50

10 ml. of a 20% caustic solution is added with thoronghstirringandthe autoeiavingiscontinuedfor 'Zminutesat'Ipounds'pressure. Thedigestis driedatroom temperature C.) under forced diaft,inthinflims(gramspersquarefooti.

15 powderedinaballmiliandscreenedthrough 100 .meshscreen. Theglueispreparedbymixingm grams of the glue powder with 100 ml. water. lt has about the consistency of average casein ghresandapHofaboutiOJ. Thegluelineof m veneersunitedasdescribedinExampleliseomparable to that of Example 2.

Example 5.200 grams of shredded fresh hoof material is mixed with 1000 m1. of a1% sodium sulfide (60% fused) solution and heated 30 minutes in an autoclave at 18 pounds pressure. 50

mLofa20% caustic solutionisstirredinandthe autoclaving is continued for '1 minutes at '1 pounds pressure. The resultant digest is dried in thin fllms, which is pulverized and screened as in 30 Example 1. Working glue is prepared by mixing 40 grams of the glue powder with ml. of water. It spreads well, is smooth, in tacklness it resembiesthebestcaseinglues andhasapHofaround 11.0. Wood veneer united in a hot press, as

35 describedinExample1,indicatedastrongerglue iineafteroniyanhoursetthanwhenimitedwith averagecsseinglue. Itmayalsoheusedto advantage as a cold glue. Water resistance of fresh glued unions is not up to standard, but

40 is improved by further set.

Emmple 6.200 grams of calcined hoof meal, the hoof meal of commerce, treated as in Exampie 5, produces a glue with pH of about 10.0, spread inferior to that of (5), strength of glue line, fair. and water resistance poor.

Example 7.--A mixed -eather digest is preparedasdescribedinExampleii. Tothisis added 200 grams of dried fertiliser blood and themixtureisspreadinthiniiims(30grams persquarefoot)todryasdescribed. Thepowder is prepared and screened as described. The workingglueispreparedbymixingfligramsof the glue powder with 100 ml. of 1% KaOH with thorough stirring. The spread is fair. The pH cold gluing, but produces glue lines with wood veneers, united by hot pressing as described in Example 1, thatareequalinstrengthandin water resistance to those produced by average so easeinglues.

l'mmple 8.Equal parts by weight of the powdered feather glue described in Example 3, and dried fertilizer blood are thoroughly mixed dry. figramsofthisminedpowderismined tic solution, allowed to stand an hour, then thoroughiy stirred to produce a working glue. This has a fair spread, although inclined to be somewhat granular and has a PE of about 11.5. Glue lines produced with it in plywood veneers united Example 9.Equal parts by weight of the powdered feather glue described in Example 3, and a commercial casein glue are mixed dry. 40 grams of this mixed powder is stirred into 85 ml. of water, allowed to stand 30 minutes, then thoroughly stirred to produce a working glue. This has about the same viscosity and spread as the casein alone and has a pH of about 12.0. Used either hot or cold, this mixture produces glue lines comparable in strength and water resistance to those of the casein glue alone. This glue is still workable after standing 24 hours, but the strength of glue lines is lower.

Example 10.Equal parts by weight of the powdered hog bristle glue described in Example 4 and dried fertilizer blood are mixed dry. 45 rams of this mixture is stirred into 100 ml. of a 1% aqueous caustic solution, allowed to stand an hour, then thoroughly stirred to produce a working glue. This has about the same viscosity and spread of average casein glue and has a pH of about 11.5. It can be used for hot pressed gluing only. It produces glue lines comparable with those of average casein glues in strength and water resistance.

Example 11.Equal parts by weight of the powdered hog bristle glue described in Example 4, and commercial casein glue are mixed dry. 40 grams of this mixture is stirred into 85ml. of water, allowed to stand 30 minutes, then thoroughly stirred to produce a working glue. This has about the same viscosity and spread as the casein alone and has a pH of about 11.0. Strength of glue lines and characteristics are similar to those of the glue described in Example 9.

Example 12.-Equal parts by weight of the powdered hoot meal glue described in Example 6, and dried fertilizer blood are mixed dry. 45 grams of this mixture is stirred into 100 ml. of a 1% aqueous caustic solution, allowed to stand an hour, then thoroughly stirred to produce a working glue. This is not as smooth and does not have as good spread as the glue of Example 6, and has a pH of 11.0 to 11.5. The strength of hot glue lines produced as described in Example 1, are about comparable to those for average casein glues, and the water resistance is comparable to that of very good casein glues.

Example 13.Equal parts by weight of the powdered hoof meal glue described in Example 6, and commercial casein glue are mixed dry. 40 grams of this mixture is stirred into 90 ml. of water, allowed to stand 30 minutes, then thoroughly stirred to produce a working glue. This has a viscosity and spread comparable to casein glue and has a pH of about 11.5. The strength of glue lines and water resistance are equal to or possibly a little better than those described in Example 12.

Example 14.-40 grams of a commercial bone lue is dissolved in 40 ml. water at 140-150 F. in accordance with usual procedure. This glue solution is cooled to about 104 F. and at this temperature is mixed with the working glue solution of Example 5, containing 40 g. keratin. The

of the bone glue alone.

mixture is heated to 140-150 F. for application. The viscosity is a little greater than that The pH is about 10.0. If used as paper adhesive,.the set is nearly equal to that of bone glue alone. After application and setting-if the paper joints are cured for 45 minutes at 176 F., water resistance is developed to the extent that the paper fails before failure of the glue line.

Example 15.40 grams of a commercial hide glue is dissolved in ml. water at -150 F. in accordance with usual procedure. This glue is cooled and mixed as in Example 14 with the working glue solution of Example 3. Viscosity of mixture at 140-150 F. and the pH is about the same as that of Example 14. It is to be noted that the glue-water ratio here is 80-180 as compared to that of 80-90 for Example 14. The glue set on paper, as well as the developed water resistance, is, however, about the same.

It is to be noted that, although glues with good properties may be produced with commercial products readily available, such as dried fertilizer blood and hoof meal, better products may result if this material is processed for glues in the fresh condition. In this way detrimental treatment of the keratins, such as excessive heating, necessary to the economical production of present commercial products, may be eliminated.

Although the keratins investigated as described in this specification are limited to chicken feathers, hog bristles and hoof material, there is no intention to so limit the scope. Chicken feathers may be considered as merely indicative of what may be expected with feathers from any fowl or bird; with hog bristles, with any hair or fur, including wool, human or animal hair; with roof material; and horn or any other animal horny scale materiaL- All of these materials are classed as keratins and are proteins with oriented molecular configuration favorable for fiber structure, as shown by X-ray diffraction patterns. These proteins are exceptionally stable and resistant to the action of recognized dispersing agents.

Having thus described this patent, what we claim for Letters Patent is:

1. A process for the production of a powdered adhesive comprising reducing a native keratin in an aqueous alkaline sulfide solution of about from 0.5 per cent to 1.5 percent concentration, dispersing the reduced product in a caustic soda solution of about 1.0 percent concentration, drying the resulting liquid at a temperature not above about 104 F., and reducing the dried product to a powder.

2. A process for'the production of a powdered adhesive comprising reducing a native keratin in an aqueous alkaline sulfide solution of about from 0.5 percent to 1.5 percent concentration, dispersing the reduced product in a caustic soda solution of about 1.0 percent concentration, drying the resulting liquid in films by circulatin air at a temperature not above about 104 F., and reducing the dried product to a powder.

GEORGE H. BROTHER. CHARLES H. BINKLEY. 

